In the production of a semiconductor device, fine processing by lithography using a photoresist has been performed. The fine processing is a processing method for forming fine convexoconcave corresponding to the following pattern on the surface of a substrate by: forming a thin film of a photoresist on a semiconductor substrate, such as a silicon wafer; irradiating an activating light ray, such as an ultra violet ray onto the resultant thin film through a mask pattern in which a pattern of a device is depicted to develop the film; and subjecting the substrate to etching processing using the resultant photoresist pattern as a protective film. Recently, however, the high integration of devices is progressed and the exposure light adopted tends to have a shorter wavelength, such as from a KrF excimer laser (wavelength: 248 nm) to an ArF excimer laser (wavelength: 193 nm). However, in these photolithography processes, due to the influence of a standing wave caused by the reflection of exposure light from the substrate or the influence of the diffuse reflection of exposure light caused by unevenness of the substrate, there is caused such a problem that the dimensional accuracy of a photoresist pattern is lowered. Thus, in order to solve this problem, a method of providing an antireflective film (bottom antireflective coating, BARC) between the photoresist and the substrate is widely studied.
Such an antireflective film is frequently formed using a heating-crosslinkable composition for preventing an intermixing with a photoresist coated on the antireflective film. As a result, the formed antireflective film becomes insoluble in an alkaline developer used for developing a photoresist. Therefore, the removal of the antireflective film prior to semiconductor substrate processing is necessary to be performed by dry etching (for example, see Patent Document 1).
However, at the same time with the removal of the antireflective film by dry etching, the photoresist is also removed by the dry etching. Therefore, there is caused a problem that the film thickness of the photoresist necessary for the substrate processing becomes harder to be secured. Particularly when a photoresist of a thin film is used for the purpose of enhancing the resolution, the problem becomes critical.
In addition, an ion implantation process in the production of semiconductor devices is a process for introducing impurities into a semiconductor substrate using a photoresist pattern as a mold. Then, in the process, for preventing the surface of a substrate from being damaged, a dry-etching process cannot be performed in the formation of a photoresist pattern. Therefore, in the formation of a photoresist pattern for an ion implantation process, an antireflective film requiring the removal thereof by dry etching cannot be used as an underlayer of the photoresist. Hitherto, a photoresist pattern used as a mold in an ion implantation process has a large line width of the pattern and was consequently seldom influenced by a standing wave caused by the reflection of exposure light from a substrate or by the diffuse reflection of exposure light due to unevenness of a substrate, so that by using a photoresist containing a dye or using an antireflective film as an upper layer of the photoresist, the problem of the reflection has been solved. However, following the miniaturization of the pattern in recent years, a fine pattern has started to be required also for a photoresist used in an ion implantation process and an antireflective film as a photoresist underlayer has become necessary.
From such a fact, it has been desired to develop an antireflective film capable of being dissolved in an alkaline developer used in the development of the photoresist and of being developed and removed together with the photoresist. Then, also conventionally, the antireflective film capable of being developed and removed together with the photoresist has been investigated (for example, see Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6). However, such antireflective films are not satisfactory in terms of applicability to fine processing, the shape of a pattern to be formed etc.
[Patent Document 1]
    U.S. Pat. No. 6,156,479[Patent Document 2]    Japanese Patent Application Publication No. JP-A-2004-54286[Patent Document 3]    Japanese Patent Application Publication No. JP-A-2005-70154[Patent Document 4]    WO 05/093513 pamphlet[Patent Document 5]    WO 05/111719 pamphlet[Patent Document 6]    WO 05/111724 pamphlet